Expansion joint



1944? H. w GREENUP El AL 2,339,556

EXPANSION JOINT Original Filed May 25, 1938 HAROLD W GQEENUP AND QUSSELLD. DYALL Patented Jan. 18, 1944.

EXPANSION JOINT Harold W. Greenup, Barrington, R. I., and Russell D.Byall, Akron, Ohio, asslrnors to The Firestone Tire & Rubber Company,Akron, Ohio, a corporation of Ohio Original application May 25, 1938,Serial No. 209,940. Divided and this application January 17, 1942.Serial No. 427.200

6 Claims. (on. 94-18) This invention relates to expansion joints andparticularly to a method of and composition for forming a rubberexpansion joint. This application is a divisionvof our co-pendingapplication Serial flied May 25,1938, now Patent No. 2,290,6l3.

One chief object of the present invention is to provide an easilypracticed method of forming an expansion joint that positively fills thejoint between the members.

Another object of the invention is to provide a spongy rubbercomposition which is easily preor a combination of accelerators whichwill produce a cur at ordinary temperatures may be pared, remainssuitably fluid to be poured into cracks, and is vulcanizable at roomtemperature.

The instant invention resides in forming a mixture of latex, acompressible porous substance and vulcanization agents capable of curingthe latex at atmospheric temperatures. This mixture is maintained fluidby a suitable stabilizer so that it can be poured into a narrow jointbetween two memberswhere vulcanization occurs to hold the compoundpermanently in position between the members.

The accompanying drawing shows a transverse section through an expansionjoint constituting an embodiment of the invention. The ends of twoconcrete blocks or roadway sections I and 2, such as are formed instreets or highways, are shown in the drawing. The ends of these blocksmust be spaced apart since the blocks expand and contract with changesin temperature. Thus the material placed between the blocks 5 and 2 mustbe compressed at times andexpanded at others if it is continually tofill the varying sized space between the blocks. or course, the blockscannot be abutted due to the variations produced in their lengths, andan open space between the blocks is objectionable for obvious reasons. Aspongy rubber composition 3 fills the space between the blocks inaccordance with the teachings of this invention. The composition must beplaced in the space while fluid when practicing the invention, for thisgreatl simplifies the production of the finished joint and facilitatesadherence between the blocks and the rubber this is prevented by the useof certain stabilizers I composition. With this purpose in view, latexis used as the source of the rubber, and it preferably i centrifugedto'increase its rubber content prior to mixing it with the remainder ofthe ingredients. However, ordinary latex may be usedwhen a thickeningagent is also present in the mixture. Proper vulcanization agents areadded tothe latex, including. sulfur and zinc oxide. In the practice of"the invention, small amounts of other vuicanizers, such as piperidiniumpentamethylene dithiocarbamate, which iscommonly referred to as pip-pip,and mercaptobenzothiazole are added to the latex so that ity can bevulcanized at ordinary temperatures. Any

tuna-accelerator such a butyl or ethyl sim'ate,

used to produce vulcanization. Since the cured product must stand bothapproximately 50% compression and extension, a compressible porous, orspongy, material is mixed with the rubbar to aid in giving the desiredcompressibility to the final product. This material is finely dividedand preferably comprises latex sponge, blown sponge, or foamed rubber,although natural sponge or other spongy substances could be substitutedtherefor. I

Aluminous cement is normally added to the mixture to dehydrate it andtosp'eed up the solidification thereof. When used, it produces a harderfinished composition.

Of course, the liquid mixture should not solidify immediately uponreceipt of the cement and in the mixture; The sodium salts ofthe-onehalf sulfate ester of a mixture of higher fatty alcohols whichchiefly comprise lauryl and myristyl derivatives, which mixture is knownas Aquarex D," and 50% ammonium oleate are two stabilizers which haveproven quite satisfactory. Any soluble soap or gum tragacanthareexamples of other stabilizers which might be used.

A specific composition of my novel product which has given desirableresults is:

Parts Centrifuged latex 166 Aluminous cement 20 Sponge rubber Ammoniumsulfate 6 Sulfur l Zinc oxide 2 Mercaptobenzothiazole .5 Pip-pip .5Aquarex D A. .5 50% ammonium oleate 8 Water 3.8

adhered to for all conditions and the invention may be practiced by useof the ingredients within the following proportions:

Y Parts Concentrated latex- About 140 to about 190 Aluminous cementAbout 16 to about 24 Sponge rubber l About 50 to about Ammonium sulfate-About 5 to about 7 Sulfur About .75 to about L25 Zinc oxide About 1.70to about 2.30 Mercaptobenzothiazole About .4 toabout '.6 Pip-pip About.4 toabout .6 I Aquarex D About .4 toabout .6. 50% ammonium oleate About6 to about 10 Water About 0 to about In preparing the composition, thelatex is first stabilized with the Aquarex D and the ammonium oleate andthen the remaining ingredients are singly or collectively added theretoin powder form. The stabilizers prevent the latex from coagulating uponthe addition of aluminous cecan be reduced proportionally. Ifunconoentrated latex is used, necessarily smaller amounts of extra waterare-added to the mix.

' The adjacent surfaces of the blocks l and 2 should be coated with aprimer prior to pouring 4 the rubber composition therein to insureproper ment as normally is the case, and also function to hold air inthe latex, thus contributing to produce the compressibility desired inthe product. Other substances, such as gum tragacanth can be used inplace of the named stabilizers.

The mixture can be prepared in two portions to insure against'undesiredcoagulation, if desired. This result is obtained by separating the zincoxide from either the sulfur or the accelerators, and the two portionswould be combined only immediately prior to pouring them into a joint.Usually the composition should be pressed into the joint and smoothedover by a trowel.

It is highly desirable that the finished prodnot be sufiiciently porousand have a quantity of air spaces in it so that the product'is suitablycompressible. Water'originally present in the fluid substance aids inthe formation of these cellular spaces so that its presence is desirableif it. does not render the mixture too fluid. In some cases additionalwater may be put into the uncured mixture. The sponge rubber alsocontributes to porosity in the finished product and this result isecured by mixing an equal weight of ammonium sulfate solution with therubber and then drying it prior to adding the sponge to the remainingingredients. Thus the ammonium sulfate coats upon the rubber particlesand acts as a coagulant when it contacts latex. This coagulating actionof the ammonium sulfate prevents latex from entering the inner pores, orcells, of the sponge particles so that the porosity of 'the spongeparticles is preserved in the product. That is, the latex particlesfirst touching the sponge are coagulated on the surface of the sponge,and they soon form a layer around the sponge. Other suitable coagulatingagents, such as sodium silico fluoride, or salts of weak bases andstrong acids, may be used in place of the ammonium sulfate when desired.

Another specific composition which has given an excellent product is: r

Inthis case the Aquarex D and the gum tragacanth are added to the latexas solutions and the sponge rubber treated as hereinbefore described.The remaining ingredients may be added in the form of aqueousdispersions. The specific proportions of the given ingredients can bevaried either way about from the given figures and the product still hasthe desired properties.

The gum tragacanth serves as a thickening agent to permit the additionof a considerable 'volumeof water to. the mixture without making themixture too fluid. Thus by decreasing the volume of water added, theamount of gum adherence of the vulcanized rubber to the blocks and thelatex mixture is poured into the joint before the primer coat dries. Theprimer may comprise latex and a silicate such as water glass. Whenaluminous cement is used it makes the water glass insoluble and aids inpermanently sealing the joint.

A particular feature of the invention is that it gives a spongy rubbermass as a finished product, which mass has the compression and expansionproperties required by building specifications. Then, too, the simplemethod of preparing the mixture as a self-curing fluid which can bepoured into a joint where it solidifies at ordinary temperatures greatlyfacilitates use of the invention.

In some cases the rubber composition 3 may be placed only in the upperportion of the joint and a compressible substance, such as particles ofsponge rubber, used to fill in the lower portion of the joint. It willbe seen that 'the rubber composition 3 can be used to fill any cracks inhighways or other structures and in each case it will form an adherent,tight seal that prevents leakage of water through the joint. Thecomposition of the invention will set permanently in the time requiredfor concrete to set so that it does not delay use thereof.

In accordance with the patent statutes, we have illustrated anddescribed the principle and mode of operation of the preferredembodiment of the invention. However, it will be understood that variousmodifications can be made without departing from the scope of theinvention as described in the appended claims.

We claim:

1. An expansion joint positioned between two spaced members, the jointcomprising a latex rubber composition which is bonded to the adjacentsurfaces of the spaced members by a latex and silicate priming coating.

2. An expansion joint positioned between two spacedmembers, the jointcomprising a latex rubber composition, which has a plurality ofcompressible porous particles embedded therein, and which is bonded tothe adjacent surfaces 'of the spaced members by a latex and water glasspriming coating.

3. That method of forming an expansion joint in an expansionspacebetween spaced members which comprise inserting a mass of particles of aporous compressible substance in the lower portion of the space betweenthe members, and introducing a quantity of latex composition into saidspace sufflcient to cover said particles and form a seal between saidmembers, said latex I composition gelling upon standing.

4. An expansion joint positioned'between two spaced members, the jointcomprising a latex rubber composition, which has a plurality ofcompressible sponge rubber particles embedded therein, and which isbonded to the adjacent surfaces of the spaced members by a latex andsilicate priming coating.

5. The method of forming an expansion joint between two spaced memberscomprising coating compressible sponge rubber particles with a latexcoagulant. mixing the coated particles with a fluid latex composition toproduce a mixture of ticles with a fluid latex composition to produceamixture of the latex composition and compresthe latex composition andsponge rubber particles having latex rubber coagulated on the surfacesthereof, introducing the mixture into-the splice between the members,and solidifying the mixture in said space.

6. The method of forming an expansion joint between two spaced memberscomprising coating particles of a compressible porous material with alatex coagulant, mixing the coated par-

